Vascular smooth muscle cells (VSMCs) are highly plastic and can oscillate between a proliferative or a quiescent, more differentiated state.
MicroRNAs (miRNAs) represent a class of small (20-25 nucleotides), non-coding RNAs that are key regulators of many cellular events, including the balance between proliferation and differentiation during tumorigenesis and organ development. miRNAs are initially transcribed as a longer primary transcript (pri-miRNA) and processed first by the ribonuclease enzyme complex, Drosha/DGCR8, and then by Dicer, leading to incorporation of a single strand into the RNA-induced silencing complex (RISC). Each of the 650 human miRNAs is predicted to interact with over one hundred target mRNAs in a sequence-specific fashion involving Watson-Crick base-pairing with nucleotides 2-8 of the miRNA. miRNAs generally inhibit target mRNAs by repressing translation or reducing mRNA stability. miRNAs may also activate mRNA translation under certain cellular conditions.